1. Field of the Invention
The present invention relates to an optical writing device to be installed in an image forming apparatus such as a printer or a facsimile.
2. Description of Related Art
One of well-known optical writing devices is that disclosed by Japanese Patent Laid Open Publication No. 1-272469. In the device, a time for scanning of one picture element is divided into some periods, and the exposure strengths in the periods are different from each other. Another of well-known optical writing devices is that disclosed by Japanese Patent Laid Open Publication No. 63-272568. In the device, a time for scanning of one picture element is divided into some periods, and the exposure times in the periods are different from each other. In both of the optical writing devices, exposure elements are turned on and off individually and selectively in accordance with image data in each of the periods so that the picture element will be provided with an accumulated exposure value corresponding to a desired level of tone. However, in the devices, toner deposition on blank regions sometimes occurs, and it has been difficult to obtain complete blank regions.